Modified atmosphere preservation of freshly prepared diced yellow onion.
Blanchard, M.; Castaigne, F.; Willemot, C.; Makhlouf, J.;
Postharvest Biology and Technology Year: 1996 Vol: 9 Issue: 2 Pages: 173-185 Ref: 30 ref.
1996
บทคัดย่อ
The influence of controlled atmosphere storage conditions on the microbiological and sensory quality and the physiology of diced, `ready-to-use' yellow onion (cv. Blitz) was investigated. In the first experiment, diced onion was stored for 14 days at 4 deg C and high RH under a continuous stream of nitrogen containing (% O2/% CO2) 20/0, 2/0, 2/5, 2/10 or 2/15. The tissue was sampled for microbiological and sensory analysis on days 0, 4, 9 and 14. In the second experiment, the diced onion was stored for 12 days at 4 deg under (% O2/% CO2) 20/0, 2/0 or 2/10. Samples were collected on days 0, 4, 8 and 12 for physiological analysis. The following parameters were studied: mesophile and psychrotroph counts, pyruvate content (an index of flavour intensity), colour, sensory quality, rate of respiration and sugar (fructose, glucose, sucrose and total sugars) concentration. CO2 enrichment of the atmosphere delayed diced onion deterioration. Microbial development was delayed, particularly that of the psych
rotroph flora. Sensory quality was optimal under the 2% O2/10% CO2 atmosphere. However, pyruvate and colour determination showed no noticeable difference between treatments, although the period of storage significantly influenced these parameters. High CO2 and low O2 delayed the rise in respiration and the reduction in sucrose content compared with the control (air). Concentrations of reducing and total sugars remained constant throughout storage under all treatments. Browning after cooking developed with increasing length of storage, but was delayed by storage under 10% CO2. Involvement of sugars in this disorder is discussed. This work provides a basis for the development of modified atmosphere packs which will extend the preservation period of the product to 2 weeks.